Precursor Phenomena of Nucleations of Quantized Vortices in the Presence of a Uniformly Moving Obstacle in Bose-Einstein Condensates

We investigate excitations and fluctuations of Bose-Einstein condensates in a two-dimensional torus with a uniformly moving Gaussian potential by solving the Gross-Pitaevskii equation and the Bogoliubov equation. The energy gap Δ between the current-flowing metastable state (that reduces to the ground state for sufficiently slowly-moving potential) and the first excited state vanishes when the moving velocity v of the potential approaches a critical velocity $v_{\rm c}$ (>0). We find a scaling law $\Delta\propto(1-|v|/v_{\rm c})^{\frac{1}{4}}$ , which implies that a characteristic time scale diverges toward the critical velocity. Near the critical velocity, we show that low-energy local density fluctuations are enhanced. These behaviors can be regarded as precursor phenomena of the vortex nucleation.     

High-throughput, high-level production of PS-tag-fused single-chain Fvs by microplate-based culture

In the present study, we investigated a microplate-based culture (MBC) of Escherichia coli for the high-throughput, high-level production of PS-tag-fused scFvs (scFv-PS) in insoluble form. The Overnight Express™ Autoinduction System (OE system) was adopted to skip the laborious induction step of the addition of IPTG. ScFv and scFv-PS began to be expressed after 6 h by conventional flask culture (FLC) and by MBC when utilizing the OE system, and similar specific productivity levels were attained during cultivation. In MBC, an important factor that directly affected the production levels was rotational speed during cultivation, suggesting that the mass transfer of oxygen was rate-limiting. In a comparison of the productivity of flask cultures utilizing the 2YT-IPTG and OE systems, MBC utilizing the OE system was the highest, with approximately 1 mg of insoluble scFv-PS obtained from each well under optimal conditions (1400 rpm). The results of SDS-PAGE and a cross-contamination check indicated that very similar cultivation conditions were attained in each well, without cross-contamination. Thus, MBC using the OE system is very useful for the high-throughput, high-level production of scFv-PS, which can be activated on the surface of hydrophilic PS plates by solid-phase refolding. Therefore, the production of a variety of specific scFv-PSs for cytokines and biomarkers will make possible the construction of sensitive and low-cost antibody microarrays, which will be very useful in clinical diagnosis and biochemical research.     

Dip Coating of Water-Resistant PEDOT:PSS Films Based on Physical Crosslinking

Water-resistant poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) films are valuable in biomedical applications; however, they typically require crosslinkers to stabilize the films, which can introduce undesired aggregation or phase separation reactions. Herein, a dipping-based process to prepare PEDOT:PSS films on nonplanar surfaces without crosslinker is developed. Sequential soaking of a dip-coated PEDOT:PSS film in ethanol and water imparts water resistance to the film. Microscopic and spectroscopic techniques are used to monitor the process and confirm that the ethanol soaking elutes the excess PSS from the film bulk, which stabilizes the film prior to the water-soaking process. The obtained films act as conductors and semiconductors on curved surfaces, including 3D-printed objects. A film deposited on a curved surface is successfully applied as the channel layer in a neuromorphic organic electrochemical transistor. This approach can enable integrated bioelectronic and neuromorphic applications that can be readily deployed for facile prototyping.     

3D Visualization of Morphological Evolution of Large Defects during Spark Plasma Sintering of Alumina Granules

The mechanical reliability of products must be assured for scaling up and production of complex-shaped components by spark plasma sintering (SPS) of spray-dried granules. The evolution of morphologies of pores and defects, which control the mechanical strength, is investigated by using synchrotron X-ray multiscale tomography during SPS of alumina granules at 1300 °C. While large defects arising from the hierarchical granule packing structure cannot be removed by pressureless sintering, crack-like defects and branched rodlike defects are almost eliminated by SPS at stresses higher than 30 and 50 MPa, respectively. But, small ellipsoidal porous regions, which may arise from aggregates or dimples of granules, cannot be removed even at a pressure of 50 MPa. A very large defect is also found by using micro-CT. It is supposed that this defect is formed from a large void in loosely packed granules. The shrinkage of large voids and the elimination of crack-like defects are explained by the theoretical prediction based on the continuum theory of sintering.     

Intercalation on Transition Metal Trichalcogenides via a Quasi-Amorphous Phase with 1D Order

Intercalation into 1D transition metal trichalcogenides (TMTs) in which fibers are bonded by a weak van der Waals force can be expected to create various intercalation compounds and develop unique physical properties according to the combination of the host materials and guest ions. However, structural changes via intercalation into 1D TMTs are not as simple as those in 2D transition metal dichalcogenides (TMDs) and are still not understood comprehensively. ZrTe₃: a typical compound with a 1D trigonal prismatic structure, belongs to TMTs. Herein, through the Ag introduction to ZrTe₃ via solid-state intercalation, a novel crystal phase with a 1D octahedral structure and a quasi-amorphous (QA) phase during the structural transition are discovered; the QA phase is a novel state of matter in which long-range order is lost while retaining 1D order. Based on the Ag concentration, the transport properties are flexibly modulated from superconductivity to semiconductivity. Density functional theory calculations indicate the attraction between Ag ions and the pair diffusion due to their attraction. Furthermore, judging the attraction or repulsion between guest ions predicts whether to induce a QA phase or simple lattice expansion like the intercalation into 2D TMDs.     

Improvement of steady-state performance for discrete-valued input control with an integrator utilizing feedback control of integrated value of input

In this study, we considered the regulator problem for discrete-valued input control with an integrator. In some cases, the state does not converge to the origin in the discrete-valued input control when the plant possesses an integrator. Therefore, a method that adds minor feedback control to the integrated value of the input was proposed. However, the effect of the feedback control of the integrated value of the input was not theoretically interpreted, and the feedback gain for the state of the integrated value of the input was designed with trial and error. Herein, we clarify the effect of feedback control on the integrated value of the input. Furthermore, we reveal that the trade-off between the steady-state and transient performances is controlled by one parameter, that is, the feedback gain for the integrated value of the input.